The present disclosure relates to seismic exploration. More specifically, the present disclosure relates to sensors and methods for high-speed (i.e., real-time) imaging-based monitoring in seismic vibrators.
In the oil and gas industry, geophysical prospecting techniques are commonly used to aid in the search for and evaluation of subterranean hydrocarbon deposits. Generally, a seismic energy source is used to generate a seismic signal that propagates into the earth and is at least partially reflected by subsurface seismic reflectors (e.g., interfaces between underground formations having different acoustic impedances). The reflections are recorded by seismic detectors located at or near the surface of the earth, in a body of water, or at known depths in boreholes, and the resulting seismic data may be processed to yield information relating to the location of the subsurface reflectors and the physical properties of the subsurface formations.
In one type of geophysical prospecting, hydraulic seismic vibrators may be used in onshore seismic acquisition surveys often referred to as a VIBROSEIS™ survey. Hydraulic seismic vibrators transmit to the earth's interior a signal for which quality may be partially dependent on the quality of the coupling between components of the vibrator and the earth, as well as characteristics of the signal (e.g., sweep) imparted to the earth. A vibrator may be described as an adjustable mechanical source that delivers vibratory seismic energy to the earth for acquisition of seismic data. Vibrators are often mounted to large trucks, the weight of which contributes to maintaining a consistent coupling between the vibrators and the earth.
When a vibrator transmits energy to the earth, the degree to which the earth approximates a spring depends on the amount of coupling between components of the vibrator (e.g., the baseplate) and the earth on which it rests. As the “springiness” of the ground changes, even with near or at surface conditions, the frequency-response of the coupling may change.
Various apparatuses and methods for seismic vibrator surveying are provided in US Publication Nos. 2010/0276224, 2012/0271551.